1. Evaluation Roots: A Wider Perspective of Theorists' Views and Influences;Alkin,2012
2. Influences on the quality of published drug studies;Bero;International Journal of Technology Assessment in Health Care,1996
3. Factors relevant to the validity of experiments in social settings;Campbell;Psychological Bulletin,1957
4. Experimental and quasi-experimental designs for research on teaching;Campbell,1963
5. Experimental and Quasi-Experimental Designs for Research;Campbell,1966